Help needed re thermostat for home made incubator

I read a whole lot of the home made incubator posts and it looked like something I could do, so I started to collect parts...

But I seem to be stumped! Most of the thermostats are described as being cheap and easily available, maybe a water heater thermotat.

I live in NZ and can find aquarium thermostats (too low), and our water heaters start at about 122 degrees F.
Everything else seems to be commercial and really expensive - i might as well go and buy an incubator, which sort of ruins the fun of making one.

So.... do you think you could post a clear picture of the device you are using, and/or a description of who normally would use it and what for? Or a website of a business that sells them where i can identify the item? Then maybe i can track one down.

I didnt have one, lol...Just used a regular bulb i stole from my bathroom light fixture, a 6 dollar thermometer/hygrometer from walmart and a tupperware bowl for water, underneath the hardware cloth i had the carton with the eggs in it on.

So how did you control the temperature?
My husband suggests something similar - put a light bulb in, check to see how long it takes to heat up and put it on a timer switch. I had visions of spending 24 hours watching it to work out the timing, and the posts seem to suggest varied temps will cause failure?
I'd love it if we could at least just start with the plain bulb...

Mine was just awesome lol...actually it sucked but since it was a regular 60 watt light bulb it didnt get that hot...I used a steriliter tub i think like a 10 gallon size-ish, and it kept it pretty darn constant at about 99 degrees, had a few spikes but i also poked some holes in the tub and if it got too cold i covered them with duct tape and if it got too hot i took the tape off. Kinda sucked cuz i had like absolutely NO life for 20 ish days cuz i watched the bator like a hawk, Didnt get an awesome hatch rate but i hatched 4 out 13

O dear, not such a great return for all that work!
But maybe worth a go if I can't get a thermostat... I guess we could at least make it up without and see how bad the fluctuation is..
I've had a look on ebay and see there seem to be some there, but they don't give enough detail for me to know which ones would suit.

For some reason I thought reptile ones weren't the right temperature either, but now I see they are about right, only here they are really expensive too!
I'll keep looking, though, thanks for the suggestion.

I've had a look at rebelcowboy's link, and maybe I was looking at the temperature thing wrong - I thought you'd want your thermostat measuring the temperature where the eggs are, but is it more that it's just a dial - measure temperature where the eggs are with a thermometer, put the thermostat where the heat source is and adjust the dial according to the reading on the thermometer? Is that more like it? So the temperature where the heat source is could be quite a bit higher than the temperature you want for the eggs? Or have i lost it again?